Non-absorbent material and process of manufacture



UNITED STATES PATENT OFFICE.

FREELAND J. MORRISON, OF CO RNELL, WISCONSIN, ASSIGNOR TO CORNELL WOOD PRODUCTS 00., OF'GIHICAGO, ILLINOIS, A CORPORATION OF WISCONSIN.

NON-ABSORBENT KATEBIAL AND PROCESS OF MANUFACTURE I No Drawing. Application filed June 9,

To all whom it may concern Be it known that I, FREELAND J. Monm- SON, a citizen of the United States, and a resident of the village of Cornell, in the county of Chippewa and State of \Visconsin, have invented certain new and useful Imirovements in Non-Absorbent Materials and rocesses of Manufacture, of which the following is a specification. 4

This invention relates to the manufacture of pulp boards and other materials consisting chiefly of cellulose or other fibrous or absorbent materials and processes form-anufacturing the same, particularly sized boards which are relatively impervious to moisture anddliquids and at the same time tough and r1 1 he princi a1 object of the invention is to provide artic es composed chiefly of fibrous or absorbent materia s which possess greater imperviousness, durability, strength j and rigidity than those hitherto'produced.

Another object of the invention is to provide a process for manufacturing such articles.

The process of manufacture will for purposes of illustration be described in connection with the manufacture of wood pulp boards made of several plies of thinner pulp boards united together, although the invention is a plicable to boards made in one operation rom wood or other pulp.

The apparatus required is so well known to those skilled in the art and so simple that it is believed that no illustration thereof will be necessary; 3 0

The separate plies are first coated wlth suitable paste and then superimposed to form a board of the desired thickness The superimposed plies are then sub ected to pressure which may be produced by a press, rolls or other suitable, means and t en allowed to set.

The board so formed is then preferably treated on both sides with the sizing solu' tion. This may conveniently be accom plished by passing the board between a. pair of rolls, the lower one of which dips into a bath of sizing solution, while such solution is sprayed onto the upper surface of the board immediately prior to its contact with the upper roll. When dried the board is ready for use.

As paste for securing the plies together, I

Specification of Letters Patent.

Patented Jan. 18, 1921.

1919. Serial No. 302,845.

prefer to employ a solution of sodium silicate to which a filler such as clay, casein or starch has been added. This paste may conveniently be made by adding sufficient clay to a 40 B.'solution of sodium silicate to bring its specific gravity up to 42 Be. Ordinarily this involves the addition of one pound of clay to each gallon of the solution em loyed.

11 other cases a paste composed of an alkali .such as caustlc soda or soda ash, an organic adhesive such as glue, and a suitable filler may be employed. The alkali aids the penetration of the glue. so that the paste so formed is superior to ordinary glue.

The sizing solution employed is adapted to make the material treated more imperviv durable,

amount of an organic adhesive such as glue.

I have also found that when such organic adhesive is employed the amount of sodium silicate which will stay in solution is reduced so that the viscosity of a solution containing both silicate and adhesive is lower than that of asaturated solution of silicate alone and is also lower than is desirable.

If the viscosity is too low there is more penetration than is necessary since the essential factor is to form an impervious or rela-' tively non-absorbent surface film and the material which penetrates the material is lost so far as the formation of a surface film is concerned- Therefore, to increase the viscosity a filler is employed which may conveniently be. a finely divided inorganic material such as pottery clay or an organic'material such as casein or starch.

Although I prefer to employ a soluble silicate in-some cases caustic alkali or other substances having an alkaline reaction such as soda ash may be used in its place. In such cases the amount of filler employed is ordinaril greater than when the silicate is emIploye t is believed that the sodium silicate by virtue of its alkaline action. acts on cellulose fibers in a similar manner to the action of caustic alkali in the mercerization of cotton. The fibers on the surface of the sheet appear to putt up and become softened so that they are readily penetrated by the solution and the pores and interstices filled by the clay, casein, starch or other material in suspension.

When caustic alkali or soda ash are used in thesizing solution substantially the same action on the fibers takes place.

The sodium silicate as its name waterglass implies, dries to a. glassy transparent mass which makes the material more impervious especially to organic liquids such as those employed in making paints, varnishes and the like. In general, organic substances are more soluble in organic liquids than inorganic liquids and inorganic substances are more soluble in inorganic solvents than organic solvents. The dried salt also has ver considerable mechanical strength.

he addition of an organic adhesive not only increases the strength of the resulting product but also on account of its colloidal properties prevents any tendency of the sodium silicate to crystallize.

The filler employed not only increases the viscosity but also fills the voids between the fibers which would otherwise have to be filled with silicate and glue. The use of such materials therefore, replaces a part of the silicate and glue.

As the sodium silicate is non-crystalline in its character, particularly in the presence of a colloid such' as glue, not only are the surface fibrous layers saturated but also the voids between the fibers are filled so that a continuous film is formed over the entire surface- This film of silicate and other materials gives a hard glass-like surface, which retards the atmospheric moisture. By reducing the penetration of paints the area which can be covered by a given quantity-of paint is increased.

Thus I have found that the amount of paint required to coat a given area of material treated with my sizing composition is much less than with surfaces treated with other sizing compositions. Further the amount of paint required is not greater six months after the size has been applied than ten days afterward. Further I have found that the appearance of a single coat of paint on a surface treated with my composition is better than that of two coats on other sized surfaces.

I have also discovered that a board satpenetration of paints, water or urated with my composition expands and contracts much less than boards treated with other sizing compositions under the same conditions.

This is probably largely due to the exclusion of atmospheric moisture by the sizing composition. The. relatively low expansion and contraction of pulp boards treated in this way makes them particularly applicable for forming the surface of room walls or the like where the boards are attached to relatively inexpansihle materials.

lVood or paper pulp boards treated with my solution are further found to be much stronger under the Mullen test than untrcated boards or boards treated with other sixin solutions.

Vhile my material is designed primarily for treating wood or paper pulp boards already formed, the material may be employed in the manufacture of such boards particularly where the boards are made of several plies of paper or thin board secured together. In such cases my sizing solution may be placed on the various plies and the whole subjected to pressure by rolls or other suitable means.

The composition is also adapted for sizing writing or other paper to render it non-absorbent and give it a smooth glassy surface.

The proportions of the various constituents employed in the solution are preferably retained within the following limits: 3 to 15% by weight of non-crystalline inorganic material such as sodium silicate; 1 to 7% of an organ: adhesive such as glue; 1 to 8% of a filler-such as clay, casein or starch and the rest water. When caustic. alkali, for example caustic soda is used, the preferred proportions are 0.5 to 3% by weight of caustic alkali, 1 to 7% of organic adhesive and 8 to 50% of a filler.

The amount of water may be varied relatively to the solid constituents but preferably the relative quantities of the various solid ingredients to each other are not changed greatly outside the foregoing limits.

In particular where sodium silicate is em-- ployed the amount of organic adhesive should not be ordinarily in excess of the weight of silicate employed. In certain cases, however, especially when sodium silicate is used the filler may be omitted entirely.

In the preferred method of preparing the composition, to gallons of cold water 37%} lbs. of high grade glue or a correspondingly larger amount of lower grade glue, are

.added and the mixture allowed to stand from 3 to 36 hours. The mixture is then heated to between to F. for about 15 minutes after which 25 gallons of 40 B. sodium silicate solution is added slowly while the liquid is being stirred. Owing to the greater specific gravity of the silicate solution the latter tends to fall through the glue solution and thereby mix with the latter. If on the other hand the glue solution is addedto the silicate solution the former being lighter will tend to remain on top and not to mix with the solution beneath. COIISGilGIItl? I refer to add the silicate to t e g ue. inally 29 lbs. of potter cla are added and thoroughly incorporate in t e mixture. In some cases the clay is mixedwith the sodium silicate solution before the latter is added to the glue. The size is then ready for use.

I am aware that numerous details may be varied through a wide range without departing from the principles of this invention and I therefore do not purpose limiting the patent anted hereon otherwise than necessitated y the prior art.

I claim as my invention:

1. A pulp board coated and partially-impregnated with a solution containing 3 to 15 parts by weight of non-crystalline inormaterial, 1 to 7% of an organic adhesive and l to 8% of a filler.

y 3. The process of impregnating fibrous or absorbent material consisting in coating'the same with a solution containing 3 .to 15% by weight of non-crystalline inorganic mate-- rial, 1 to 7 of an organic adhesive, and

-1 to 8% of a filler, and subsequently compressing the material.

In testimony whereof I have hereunto subscribed my name in the presence of two sub scribing witnesses.

, FREELAND J. MORRISON. Witnesses:

RInsnAnE Ennis, EARL M. HARDINE. 

